We are requesting two years of funding to complete a clinical trial investigating the potential mechanisms of change in Cognitive Therapy for depression. Although all data collection procedures for the acute treatment phase of the study will be complete by the end of the current funding period, we need funds to complete a two-year follow-up, reduce and analyze follow-up data, and disseminate the findings. We have assigned depressed outpatients (N+152) to receive: (1) interventions aimed at activity scheduling and increasing pleasant events (the AC or "behavioral activation" treatment, , testing an activation hypothesis for the efficacy of CT); (2) interventions aimed at behavioral targets and the examination/modification of dysfunctional automatic thoughts (the AT treatment, testing a "coping skills" hypothesis for treatment efficacy); or (3) interventions aimed at behavioral activation, automatic thoughts and the structural modification of depressive schemas. This latter treatment represents standard CT. If Beck's hypothesis about the efficacy of CT is correct, the CT condition which includes schema modification should prove to be more durable in its ability to prevent depressive relapse, and might also be expected to outperform BA and AT during the acute treatment phase. A second aim of the study has been to ascertain the degree to which all three treatments result in 1) behavioral activation; 2) increased ability to cope with depressogenic automatic thoughts; and 3) the extent to which core schema regarding the self are modified during the course of therapy. The assessment of these client changes provides a second, correlational examination of the processes leading to change during CT.